How to access PHP environment variables in a bash script?

Question

I'm writing a bash script meant to run on a remote AMP stack. The script needs to access a PHP predefined environment variable ($_ENV).

This is what I want:

db_host=$(php -r 'echo $_ENV{DATABASE_SERVER};')
echo "The DB Host is: $db_host"
# output: "The DB Host is: internal-db.s173785.gridserver.com"

This is what I get instead:

# METHOD 1
db_host1=$(php -r 'echo $_ENV{DATABASE_SERVER};')
echo "The DB Host is: $db_host1"
# output: "The DB Host is: "

# METHOD 2
db_host2=`php -r 'echo get_env(DATABASE_SERVER);'`
echo "The DB Host is: $db_host2"
# output: "The DB Host is: "

Neither method works, both variables return empty. I know that this PHP variable is set, because when I type this into the terminal (after ssh'ing into the server), I get the expected value:

$ php -r 'echo $_ENV{DATABASE_SERVER};' 
# outputs: "internal-db.s173785.gridserver.com"

Technically the above methods should work, because I managed to get this working in my script:

php_user=$(php -r 'echo getenv("USER");')
echo php_user is $php_user
# outputs: "php_user is myusername"

Anyone know what I am doing wrong?\

***UPDATE*******

I should mention that I am invoking this script from my local machine like so:

ssh -t [email protected] "myscript backup_remote_db"

"myscript" is the name of my executable bash script, and "backup_remote_db" is the function I'm passing to it which contains the code above.

This might not be cause however, because when I echo $USER in the script, it echoes the remote user, not the local one...

***UPDATE 2******

Here is how I finally got it working:

db_host=$DATABASE_SERVER
echo "The DB Host is $db_host"
# output: "The DB Host is: internal-db.s173785.gridserver.com"

But only if I make this adjustment to how the script is invoked:

ssh -t [email protected] ". /etc/profile; myscript backup_remote_db"

Are you sure, that script runs with same environment? may be it runs from other user or something like this? — vp_arth
– vp_arth, Commented May 8, 2014 at 11:45
Where is DATABASE_SERVER set in the first place? Your .bashrc perhaps? — Ja͢ck
– Ja͢ck, Commented May 8, 2014 at 11:46
So then you need to have . /etc/bash.bashrc in your script and then you can use $DATABASE_SERVER. — Ja͢ck
– Ja͢ck, Commented May 8, 2014 at 11:54

vp_arth · Accepted Answer · 2014-05-08 11:48:26Z

5

You don't need php for get environment variables in your shell

Just print it:

 echo "The DB Host is $DATABASE_SERVER"

And for full answer, I assume, that php doesn't work because you get notice Use of undefined constant PATH, you should wrap your string arguments.
This should work:

v=$(php -r 'print_r(getenv("DATABASE_SERVER"));')
echo "DB: $v"

Update: .bashrc is not sourced when you log in using SSH. You need to source it in your .bash_profile like this:

if [ -f ~/.bashrc ]; then
  . ~/.bashrc
fi

edited May 8, 2014 at 11:48

answered May 8, 2014 at 11:37

vp_arth

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6 Comments

Daniel W. Over a year ago

When using single quotes in bash's echo, the $v doesn't get interpreted (it prints DB: $v) whereas with double quotes it prints the expected output.

JP Lew Over a year ago

unfortunately this is not working for me, v still comes up blank

JP Lew Over a year ago

cat ~/.bashrc gives: No such file or directory. I can't find the .bashrc

vp_arth Over a year ago

simple change it to /etc/bash.bashrc

JP Lew Over a year ago

@vp_arth yep, this is the answer. I finally found the dotfile I needed, it was /etc/profile. I update my bash script to include . /etc/profile before running the script, and now it works. So you taught me two thing: first, environment variables exist independent of PHP. Second, there's a difference between executing a command via ssh, versus when ssh'ing into a server via command line. In the latter case, it sources all kinds of dot files behind the scenes. Thanks everyone.

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